1. Field of the Invention
The present invention pertains to a method for removing overburden in a surface mining operation using blast casting and blast fragmentation of the overburden together with mechanical excavation to reduce the overall excavating effort in exposing a coal or other mineral seam of substantial width.
2. Background
The time and effort required to move overburden material away from a mineral seam in the earth is important with respect to the efficiency of large scale surface mining operations, in particular. The development of ever larger mechanical excavating apparatus such as dragline type excavators has made available the opportunity to increase the width of a coal seam or similar mineral value that may be uncovered in one cycle of a typical surface mining method. However, the increased width of a so-called "panel" of overburden material that may be removed in one cycle of operation has given rise to certain problems in utilizing blast casting techniques and in fragmenting the overburden material in preparation for excavation. In particular, limits on the width of a panel of overburden material which may be blast cast into an adjacent pit have brought on the need for developing a method for uncovering relatively wide segments of coal and similar mineral seams. It is to this end that the present invention has been developed to provide an improved method for removing overburden from coal seams and similar excavating operations.